list1=[eval(x) for x in input().split()]
list2=[eval(x)for x in input().split()]
list4=[]
i=1
j=0
while i<list1[0]+1:
    if i not in list2:
        list4.append(i)
    i+=1
if len(list4)==0:print('0')
else:
    while j<len(list4)-1:
        print(list4[j],end=' ')
        j+=1
    print(list4[j])
    